The magnetic canopy of big sunspot AR1618 is crackling with M-class solar flares. This image taken by NASA's Solar Dynamics Observatory shows the extreme ultraviolet flash from one of them, an M1.6-class flare on Nov. 20th at 1928 UT:

This eruption, and another one like it about 7 hours earlier, might have propelled faint coronal mass ejections (CMEs) toward Earth. If so, the impacts would likely commence on Nov. 23rd, with a chance of high-latitude geomagnetic storms following their arrival.

As the sunspot evolves, so does its intense magnetic field--and this means strong flares are in the offing. Fast-changing magnetic fields on the sun have a tendency to reconnect and erupt. NOAA forecasters estimate a 70% chance of M-class flares and a 15% chance of X-flares during the next 24 hours. Because of the sunspot's nearly central location on the solar disk, any eruptions will likely be Earth-directed. Stay tuned for updates. www.spaceweather.com